Percutaneous transluminal coronary angioplasty (PTCA) is used to reduce arterial build-up of cholesterol fats or atherosclerotic plaque. A percutaneous introducer sheath is used to access the vascular system of the patient and acts as a means for introducing and positioning guiding catheters and other interventional devices within the patient. The introducer sheath is a tube-like member which is partially inserted into the vasculature at a puncture site, typically in either the femoral, brachial, or radial artery of the patient. The proximal, or working end, of the introducer sheath is accessible outside of the vasculature for the introduction of interventional devices through the sheath. Typically a guide wire is inserted through the introducer sheath and subsequently steered through the vascular system to the site of therapy. A guiding catheter, for example, can then be advanced through the introducer sheath and over the guide wire. The guiding catheter acts as a support conduit for therapeutic interventional devices such as balloon catheters. The balloon catheter is inserted through the guiding catheter and over the guide wire. The balloon at the distal end of the balloon catheter is inflated, causing the site of the arterial stenosis to widen.
An introducer sheath contains an access lumen for introduction of interventional devices, a luer hub for connection to syringes and other peripheral devices, and a hemostasis valve to prevent blood loss from the lumen of the introducer sheath. Typically, the PTCA procedure involves an initial diagnostic assessment of the extent and location of the arterial stenosis. To accomplish the diagnostic assessment, an introducer sheath is selected which will accommodate an angiographic catheter, which is typically of a 5F-7F (0.065-0.091 inches) outer diameter. Once the assessment is complete and the practitioner has determined that therapeutic intervention will be performed, the introducer sheath is typically replaced with a larger introducer sheath which will accommodate a guiding catheter of 8F-10F (0.104-0.130 inches) outer diameter. The practitioner will generally not insert the larger introducer sheath at the outset of the diagnostic assessment because of increased complications which result from the use of a larger puncture wounds in the vasculature.
Percutaneous introducer sheaths are known in the prior art. U.S. Pat. No. 5,318,588, issued to Horzewski et al., discloses, at column 12, lines 1-18:
"an intravascular sheath consisting of a shaft and a proximal hub. The shaft is composed of an inner tubular element 100 and an outer tubular element 101 . . . The inner tubular element 100 is designed to accommodate positive radial expansion over a specific range of dimensions. This is accomplished by constructing the element with overlapping surfaces and disposing at their interface a ratcheting mechanism consisting of a series of longitudinally disposed teeth 103 and a latch 102. The passage of a device therethrough of larger profile than the baseline luminal profile of the shaft engages latch 102 with successive teeth 103 and thereby radially expands the shaft of the sheath and maintains the shaft in its expanded configuration." PA1 "an elongate dilation tube 10 and an elongate expansion member 12. The expansion member 12 includes an outer tube 30 and an inner rod 32. The dilation member 12 may be inserted into the axial lumen 22 of the dilation tube 10, resulting in expansion of the dilation tube. After the dilation tube 10 has been expanded, the inner rod 32 may be removed, leaving an expanded access channel 22 which is maintained by the outer tube 30." PA1 "the large-diameter expandable sheath 11 consists of an elongate sheath tube 12 having proximal and distal extremities 13 and 14 and having a flow passage 16 having a maximum diameter extending therethrough . . . The distal extremity of the sheath tube, as shown in FIG. 4, is pleated or folded longitudinally to provide wraps or folds 17 for a distance of approximately 10 centimeters from the distal end to provide a distal extremity of reduced diameter, for example a reduction of the outside diameter from 3/8"" to 3/16" or approximately one-half the original size."
U.S. Pat. No. 5,183,464, issued to Dobrul et al., discloses, at column 9, lines 27-50, a percutaneous penetration apparatus which includes:
U.S. Pat. No. 5,256,150, issued to Quiachon et al., discloses at column 3, lines 3-24:
What is needed is a percutaneous introducer sheath which is adjustable in lumen size so that a range of interventional devices, from diagnostic to therapeutic, can be accommodated with a single percutaneous introducer sheath. Such a device would by design minimize the size of the puncture wound at the point of vascular access and would obviate the need to exchange from a smaller sheath for introduction of diagnostic devices, to a larger sheath, for therapeutic devices. Clinical studies have shown that the formation of thrombus and associated complications within the vasculature during PTCA procedures is attributed in part to the introduction and removal of interventional devices, such as introducer sheaths, from the vasculature. Consequently, if a single introducer sheath can be employed for both diagnostic and therapeutic procedures without the need to exchange the introducer sheath to accommodate therapeutic interventional devices, then patient complications during PTCA can be reduced.